Three things about Chicago's new downtown Millennium Park are well known: It's spectacular, way over budget (original estimate: $150 million, final cost: $475 million) and four years overdue.

Three things about Chicago's new downtown Millennium Park are well known: It's spectacular, way over budget (original estimate: $150 million, final cost: $475 million) and four years overdue. But here's something you probably don't know about this 25-acre public space: It's the product of a public-private partnership, with private donors paying nearly half the cost. From the start in 1998, Mayor Richard M. Daley wanted the private sector involved in the park, which was built on the site of an old railroad yard. His original idea: Donors might chip in $30 million. Corporate executive John Bryan, who led the private-sector fund-raising effort, had a different idea. "I thought the [mayor's] figure was way too modest," he said. Bryan was right. Corporations, foundations, wealthy individuals and nearby real estate interests wanted something that could transform Chicago into a world- class arts capital. The result is a lush, interactive public space that the New York Times recently called "a sculpture garden on steroids."

FOR A GOOD TIME, DIAL 311

Sometimes the most revolutionary innovations come in very small packages. Take the telephone number 311. Cities started using the number years ago to spare their 911 police and fire dispatchers from non-emergency calls. Then cities expanded it to become a customer- friendly gateway to city agencies. In its third iteration, 311 systems became management tools as governments realized that complaint calls could be tracked. That is, using computer logs, you could measure how long it took to fill a pothole from the time it was called in until the asphalt was tamped down, and therefore tell how well individual agencies were performing. Now, we may be reaching a fourth stage with 311, as it becomes a conduit to city life. New York City has announced it will link its 311 system to a database maintained by the tourism and convention bureau to tell callers which Broadway shows are sold out, where in their neighborhood they can get a late-night supper, which outdoor concerts have been rained out and the subway stop that's closest to the excursion boats for Liberty Island. Says the city's director of information technologies, "I think it's a natural progression of what we've already put in place." Others beg to differ. "311 is supposed to be a government service, and in our city, that's expansive," one city council member said. "But I don't think that means restaurant deals, tourism and boat rides on the Circle Line."

GIVING UP AN ILLUSION

San Francisco is a beautiful city with an ugly problem: the 15,000 homeless people who are camped out on its streets, plazas and parks. Gavin Newsom ran for mayor last fall on the promise that he'd end the homeless problem in San Francisco. On taking office, he convened a 33- member task force to tell him how to make good on that promise. Six months later, the recommendations are in. Boldest among them: Provide the city's 3,000 "chronically homeless" people with permanent housing that includes on-demand drug and alcohol treatment and medical care. In other words, the task force said, give up the illusion that these are people who are temporarily down on their luck and treat them as wards of the city. Wouldn't this cost San Francisco a fortune? Yes, but less of a fortune than is currently being spent, the task force decided. That's because these 3,000 are already consuming 63 percent of the money spent on homeless services, as they shuttle between the street, homeless shelters, soup kitchens, jail and hospital emergency rooms. If a chronically homeless person spends time in the hospital or jail, he can cost the city up to $61,000 a year. By placing him in supportive housing, the cost can be lowered to $12,000 to $16,000 a year, allowing more to be spent on the temporarily homeless.

THE GATEWAY EXODUS

The U.S. Census Bureau released a new batch of population estimates the other day, and much of it was just what you'd expect: Sun Belt cities grew faster than places in the Midwest and Northeast, and suburban cities with lots of cheap new housing grew faster than central cities. What about the great surprise of the 1990s: the revival of growth in big cities? It's still going on, although at a slightly slower pace. But then there's St. Louis, which continues losing population at a fearsome rate. Since 2000, St. Louis has bid farewell to 4.6 percent of its population. Reaction by local officials to the dismal news: Mayor Francis Slay simply refused to believe the census estimates, calling them "bogus and unreliable." He has been looking at building permits, he said, and they indicate that "the downward population spiral has stopped, and we are actually beginning to see increases." Slay's planning director said the estimates might be true, but St. Louis looks bad only because other cities, such as Atlanta and Phoenix, have annexed their way to growth. "Imagine if St. Louis amalgamated Ladue and Webster Groves, which is what the size of the city would be if we amalgamated as Phoenix did."